1. Field of the Invention
The invention generally relates to a recording apparatus such as an ink-jet printer and a method for controlling the recording apparatus.
2. Description of the Related Art
In a typical inkjet recording apparatus, a recording head attached to a carriage ejects ink onto a recording medium placed on a platen to form a line of an image on the recording medium while reciprocating the carriage in a main-scanning direction (i.e., a carriage traveling direction). Thereafter, the line of the image is repeatedly formed on the recording medium while the recording medium is transferred in a sub-scanning direction (i.e., in a direction perpendicular to the carriage traveling direction) using a transfer roller, to thereby form a complete image on the recording medium. Note that the platen is a supporting member to support the recording medium while the ink is ejected onto the recording medium.
In the inkjet recording apparatus, a relative distance between the platen and the carriage may vary with a position of the carriage in the main-scanning direction due to an assembling error of the carriage, deterioration in sliding bearings of the carriage with aging, and the like. When the relative distance between the platen and the carriage has varied with the position of the carriage in the main-scanning direction, the ink is ejected at positions differing from desired ones (ideal positions) on the recording medium. Thus, it may be difficult to form the image with high resolution and stability.
Note that the above inconsistent distance between the platen and the carriage may also occur when the platen is shifted in the main-scanning direction. Similar to the carriage case, the platen may be shifted in the main-scanning direction due to an assembling error of the platen, aging of the platen, and the like. Further, if the platen is composed of plural plate-like members, the plate-like members may be shifted with different angles in main-scanning directions. If the platen is shifted in the main-scanning direction, or the plate-like members of the platen are shifted with different angles in the main-scanning directions, the relative distance between the platen and the carriage varies with the position of the carriage in the main-scanning direction. As a result, even if the image is formed by reciprocating the carriage that is not tilted in the main-scanning direction, the ink may be ejected at positions differing from desired ones (ideal positions) on the recording medium, which makes it difficult to form the image with high resolution and stability. That is, when the relative distance between the platen and the carriage varies with the position of the carriage in the main-scanning direction, the positions of ink droplets are shifted from the desired ones (ideal positions) on the recording medium. Thus, it may be difficult to form the image with high resolution and stability.
Japanese Patent Application Publication No. 2008-221729 discloses technology for enabling registration adjustment corresponding to an irregularly uneven recording medium in a main-scanning direction of a recording head while forming an image on the recording medium.
With this technology, a user configures a recording apparatus such that test patterns are formed at two or more positions including projected portions and recessed portions of the irregularly uneven recording medium while reciprocating the recording head in the scanning direction. The test patterns are formed at the two or more positions set by the user on the recording medium by printing in forward and backward traveling directions by making the printing time in the backward traveling directions different from the printing time in the forward traveling directions. The registration adjustment corresponding to the printing on the irregularly uneven recording medium in the backward traveling direction is made based on the printing time at which an optimal test pattern is made. Accordingly, the registration adjustment is appropriately made when the irregularly uneven recording medium is used, and ink droplet shifts (i.e., print shifts) on the recording medium obtained while printing in the reciprocating directions may be reduced.
In the disclosed technology, however, the user needs to set the positions on the recording medium at which the test patterns are formed, which may be burdensome for the user.
Moreover, the platen used in the disclosed technology is made as a single unit, and if the platen is made by connecting plural plate-like members in the scanning direction (carriage traveling direction), the print shifts may not be controlled by the disclosed technology.